The present invention relates generally to a fluid flow control valve, and more particularly concerns a novel arrangement for a fluid control valve and an actuating mechanism for permitting high volume fluid flow, and a hold-open latch and safety for same.
Fluid flow control valves, such as would be used for dispensing oil and other automotive fluids in a vehicle servicing facility, are generally known. Automotive fluids range from those which are light and easy to move, such as air and water, to heavy, high viscosity fluids such as oil, grease and the like. The latter demand high pumping pressure to achieve even moderately adequate flow rates.
A typical fluid flow control valve for such applications comprises a reciprocating push rod for moving a valve seal off of a valve seat. The push rod has a slip fit within a bore in the control valve body to keep the push rod centered and aligned. The push rod is either secured to or engages the valve seal. When the push rod is moved axially, the valve seal is unseated off of the valve seat, permitting fluid flow through the valve. The push rod has a blind hole drilled down the center line and cross holes or broached notches opening into the blind hole to create a fluid flow path to the outlet of the valve body. Unfortunately, this fluid flow path through the push rod is tortuous and restricted. Thus, known valve mechanisms are plagued by low flow rates and high operating pressures which are required to overcome the pressure drop through the valve. Further, the push rod being guided by the valve body to effect linear operative motion frictionally increases actuation force causing wear and preventing smooth action of the actuating mechanism.
In most cases, fluid flow control valve actuating mechanisms have neither a safety nor a latch. Some may have only a latch and some may have only a safety. Occasionally, such actuating mechanisms have both features, but are difficult or inconvenient to operate. Moreover, when a latch is deemed useless or unnecessary, the latch mechanism cannot be disabled.
For the foregoing reasons, there is a need for a fluid flow control valve and actuating mechanism capable of high flow rates and low operating pressures, even for high viscosity, difficult to move fluids. The valve and actuating mechanism should operate smoothly with minimal frictional resistance. The actuating mechanism should also include a latch mechanism for holding the mechanism in the operatively open position. A safety may also be provided to prevent accidental operation of the valve. The operation of each of the latch and safety must be simple and convenient. The latch mechanism should be configured so that it can be disabled when necessary.